Optimized for IE used to be what the cool kids did because it supported iframes before Netscape and all of a sudden it wasn't a big deal to use frames in that way. It took a while before div based layouts actually were easy to get working in most browsers to the point where most people stopped using Photoshop and cutting everything into borderless tables.
I'm not afraid to admit that I still do table-centric HTML design on occasion (disclaimer: for specific, usually non-public, uses); it's really not all that much worse semantically than the current trend of "oh I'll assign a grid-three-seventeenths-or-whatever-the-fuck CSS class to this div in WangularStrap.js", considering that in both cases you're embedding formatting information in the data being presented (and therefore totally missing the point of "semantic" web programming).
"Social media are computer-mediated tools that allow people to create, share or exchange information, ideas, and pictures/videos in virtual communities and networks." (Someone added "Web 2.0" later there but it's immaterial. Well, HN lets you vote without refreshing the page, I guess that's "Web 2.0")
The content is driven by users, either by creating (FB, Twitter) and/or curating it (Pinterest AND HN) -> Social Media
http://en.wikipedia.org/wiki/Bulletin_board_system ("A bulletin board system, or BBS, is a computer server running custom software that allows users to connect to the system using a terminal program. Once logged in, the user can perform functions such as uploading and downloading software and data, reading news and bulletins, and exchanging messages with other users through email, public message boards, and sometimes via direct chatting.")
HN is actually a fairly primitive BBS running over TCP/IP.